原料气压缩机4级缸活塞杆断裂原因分析

Cause Analysis of Piston Rod Fracture of 4-stage Cylinder of Feed Gas Compressor

通过对某燃气有限公司原料机4级缸活塞杆断口表面及夹杂物检查、金相组织及硬度测试、力学性能测试、化学成分分析等技术检测手段进行一系列的原因分析,初步认定为送检活塞杆断口为疲劳断裂,疲劳源位于活塞杆淬硬层表面;实验数据显示,送检活塞杆的淬硬层硬度、基体硬度、基体抗拉强度均低于标准值要求,基体屈服强度仅处于标准值下限,致使活塞杆中部受到弯矩作用与填料发生偏磨,从而萌生磨削裂纹后在拉压交变工作应力作用下发生疲劳断裂。

Through a series of reasons analysis on the fracture surface and inclusion inspection,metallographic structure and hardness test,mechanical properties test,chemical composition analysis and other technical detection methods of the piston rod of the fourth-stage cylinder of a fuel gas company,it is preliminarily determined that the fracture surface of the piston rod sent for inspection is fatigue fracture,and the fatigue source is located on the surface of the hardened layer of the piston rod.The experimental data show that the hardness of hardened layer,matrix hardness and matrix tensile strength of the piston rod are all lower than the standard value requirements,and the matrix yield strength is only at the lower limit of the standard value,which leads to eccentric wear between the middle part of the piston rod and the packing,and then fatigue fracture occurs under the action of alternating working stress of tension and compression after grinding crack initiation.